The patient underwent a left nephrectomy, and histopathology evaluation confirmed renal cell carcinoma with a large necrotic component.

It should noted that central necrosis is common in large renal cell carcinomas and may mimic a Bosniak class IV cystic renal mass. So, as a rule, if the enhancing solid component volume of a renal cystic lesion is more than 25% of all mass volume, the Bosniak classification should not be used, and the mass should be instead categorized as a solid renal mass with cystic/necrotic changes; because a solid renal cell carcinoma with cystic/necrotic changes has a poor prognosis compared to the renal cell carcinoma that is arising from a Bosniak class IV cystic renal mass ¹.